Tegory (rings 1 and 2), deviation from average GC content (ring 3), and GC skew (ring 4). All plasmids are represented at 10 scale for visualization except pREB9 at 500. Color codes are as follows: turquoise, small-molecule biosynthesis; yellow, central or intermediary metabolism; orange, energy metabolism; red, signal transduction; light blue, DNA metabolism; blue, transcription; purple, protein